Was Chapek given a chance? Was he constrained by Iger? I don’t know the answers.
Chapek has never particularly been a popular figure among Disney fans for a multitude of reasons, but primarily because he just isn't very good at fulfilling either Disney CEO type.
CEOs for the company have usually come as one of two types: the ones who're very creative and love the story aspect of the company (your Walts and your Michael Eisners) and the ones who're more focused on the business and what revenue could be derived from their products (your Walker's and Iger's). Both types had different motivations, but what they did have in common was an ability to properly communicate to the public and to the company as a whole what it was they wanted to do and what their goal and vision was.
Chapek was neither type and hilariously bad at the communication part.
Chapek showed little interest in the artistry of Disney and he showed very little skill as a businessman at the same time. Sure, he was dumped with a lot of Iger's decisions, but he made several decisions of his own that proved to be quite bad ones. Not to mention he had a nasty, nasty habit of putting his foot in his mouth and saying things that reflected very poorly on the company and himself.
Iger has many, many, many faults. And unfortunately since he's come back for a second round, those faults have been more prominent. But it also cannot be ignored that he ushered in the most financially prosperous era of Disney's entire history all while also maintaining a generally well made product (even if it didn't quite match the company's previous peaks in the creative department). He showed that someone could be business oriented without also making themselves and the company look foolish, and Chapek spent his entire brief tenure as CEO demonstrating that that is kinda all he was able to do.
He was given a chance. People didn't like him going in, but most people were cautiously optimistic about a shakeup and new set of eyes on everything. He just kept proving over and over and over again why he wasn't cut out for it and people kept losing their patience with him more and more.
Frankly, for all the problems I have with Bob Iger (and there are tons), I'd rather have him than I would Chapek because Bob at the very, very least knows when it's time to shut up and just make a pivot and try something else. Chapek has no clue when it's time to shut up and reassess something.